FruityOne

This is the first time I've ever had a code on my GTA, and its throwing a code 36. I know that 36 is related to the MAF burn off relay, or MAF power, not sure exactly which. Is there a method, or process where I can test it to find out if my MAF sensor is bad?

After looking closely at the cluster of relays by the driver side firewall I noticed that the wires leading to the Fuel pump relay are REALLY stiff and corroded. Is there a way I can order a new connector for that? Whats the part number?

9D1BURD

Sorry to hear that bill, i know i had to splice news wires in for my fuel pump relay. I just went to the junkyard and cut a decent plug off.

Maybe those emission people made your car mad? so it threw a code?

FruityOne

Yeah! Those bastards!

Vader

F1,

Get out your trusty DVM. Check the burnoff circuit voltage when the engine is shut down.



If the burnoff voltage doesn't appear on pin 'D' of the MAF within 20 seconds of shutting off, you may have a MAF burnoff circuit problem, or an oil pressure switch problem. If the voltage isn't present, test the relay itself first. You can replace it with a spare or exchange it with the fuel pump relay for testing purposes. If the error code changes to a '34' or disappears, replace the relay. They're about ten bucks.



The wires can be stiff and still be serviceable. There is a corrosion prevention grease in the relay socket contacts, so don't be alarmed if you see it in there. If it's all dried, crusty, and dark, clean out the grease with mineral spirits and a small stiff brush. Pack some clean white lithium grease or silicone dielectric (tune up) grease in there.

If you still have the problem, you may have a MAF failure, but verify the burnoff voltage to the MAF first. If you have a good relay and still don't get the burnoff voltage, you may have an issue with the auxilliary oil pressure switch. That circuit signals the ECM to burn off the MAF hot wire. There have been cases where the pressure switch is intermittent and interrupts the burn off cycle.

FruityOne

Oil pressure switch huh? Would it interest you to know that my Oil Pressure gauge pegs itself the minute I start the engine? Straight past 60psi on its way to infinity.

maverick544

The SES light only comes on if a relay is bad or something electronic right? Is it possible to have a relay be bad but the SES light not to come on?

T/A gets T&A

OK, I'm bringing this one back.

I've got the same problem on my '89 IROC 5.7L, and I get nothing out of my test light checking pin D at the MAF connector after shutting down the engine. I just replaced the MAF burn off and power relays, and the MAF sensor is no more than a year old. Where is the oil pressure switch? I noticed that the wires at the connector for the burn off relay look pretty shabby. Might it be something this dumb? Also, which wire becomes hot from the relay when the burn off function begins? Vader, you're the man! What have you got on this one? Help a fellow cheese head out!

Edit: I took apart the relay connection and cleaned it out with paint thinner. I also cleaned the wire connections with the same. I reinstalled everything as it was before, but can get NO VOLTAGE to the burn-off wire (dark blue) at the MAF. I can feel the relay click as soon as the engine is turned off, but still, no voltage. I don't see a dark blue wire at the relay connection either, or I would have run a continuity test. I was able to push voltage through the black/white wire from the relay to the MAF. What's the deal?

Vader

T/A T&A,

Anything for a fellow enzyme eater.

Cheese is, in essence, a culture created by enzymes and milk. Therefore, the term "Cheese Head" has the connotation of a "cultured cranium", as it were. And they think they're insulting us. Of course, that should never be confused with "head cheese", which is a different substance entirely, and quite tasty if the right hog was butchered. As long as one doesn't get a large fragment of eyeball in one's sandwich, everything remains under control and digestable.

At any rate, you auxilliary oil pressure switch serves two functions. It supplies auxilliary power to the fuel pump in the event the relay fails, and signals the ECM when the engine has shut down. When the ignition power goes low, and whenever the oil pressure switch opens within 20 seconds of that power-down, the ECM will initiate a MAF hot wire burn off cycle. If the oil pressure switch does not open (drop power) within 20 seconds, the cycle will not initiate. If the oil pressure switch inadvertently closes after opening within that time, the cycle will be interrupted. In either case, after several shut down cycles with no burn off cycle being completed, the error code will set. For a successful MAF burn off cycle, power must also be applied to the 'E' terminal on the MAF sensor through the normally closed contacts of the MAF power relay.

Therefore, the oil pressure switch must be functional and not intermittent, the MAF burnoff control relay must be functional, and the MAF power relay must be fully functional. During the burn off cycle, the MAF will output a high flow reading to the ECM to confirm a burn off cycle. If there is no power at the MAF 'E' terminal, this signal will not be sent to the ECM, and the error code will set as well.

T/A gets T&A

So even though I feel the relay 'click' as it should, there still may be no signal getting to the ECM telling it to begin the burn-off cycle?

Is this the oil pressure switch located near the oil filter? Thanks so much for your help!

T/A gets T&A

Ok...now I'm getting a more than a little frustrated. Vader, I used your MAF Power diagram and have replaced the MAF power and burn-off relays, the oil pressure switch, and the fuel pump relay. I have run continuity checks on every wire on that diagram and have found nothing wrong. I also ran tests from the relays to the ECM. Nothing wrong there either.

I went in to talk to some technicians at the local GM garage about the burn-off function. One told me that the burn-off function only works for about 3/10ths of a second after the key is switched off. True? They also told me that there was no way to convert my car to speed density. Now we all know that's not true, and there were THREE technicians telling me that! Doesn't that make you all feel better?

I've also developed a 'stumbling' problem during operation, more so on acceleration. This didn't happen until after I put my K&N filters in the car. Could the filter oil be messing with the MAF element coating it and making the computer throw a code 36? Or, could this problem with stumbling be more fuel related? I've yet to check out my injectors, but I know they're the crappy multec ones. Might the ECM have failed on the burn-off circuit function?The ignition and plugs are all new, so I doubt it's a spark problem. Thanks for any help!

(edit): I just checked the injectors. All of them read between 17.9 and 18.2 Ohms. That might be the best thing I've heard all day!

Vader

I'm not surprised that you got misinformation from the dealer service technicians. This isn't a condemnation of their training, nor abilities, either. They probably knew all about the systems at some time in the past. They've moved on to bigger and better things and likely forgot most of what they might have known about them at one time. They also were probably never trained so intensely on one particular system, since they are expected to diagnose and repair everything from sun viso vanity lights on Geo Metros to two-speed full-screw axles on medium trucks.

There, now that I've given them an excuse, what the hell were they thinking? If they didn't know, they should have said so! We ALL know that an ECM conversion can be done with a little dilligence.

As for the MAF burn off cycle, it DOES NOT start right after teh ignition is turned off. I've already described the operation as tested and verified on my '86.

You should connect a meter to the 'D' amd 'A' terminals on the MAF (while the MAF is still connected). If you have a second meter, connect it to the 'B' and 'C' terminals to monitor the MAF output signal. Start the engine, allow it to run until it's at closed loop, then shut it off while monitoring the meter(s). You should see 12VDC at the 'D' terminal when the fuel pump stops running, and should also see a MAF output signal at the 'C' terminal once the hot wire is incandescent.

As for the poor operation, if the MAF hot wire starts accumulating a debris or oil film, the sensor will report a lower intake flow (and lean the mixture accordingly). That's the whole purpose of the burn off cycle in the first place - to keep the sensing hot wire cleaned.

T/A gets T&A

Bingo...that's it! And to think I ripped apart the whole upper wiring harness trying to find the problem.

I got the 12V for the burn off at the MAF with it connected, but there wasn't anything going on inside the sensor. THAT, sir, is the problem. I believe I had between 4 and 5v for the MAF output. I'll have to get a new MAF tomorrow. Hopefully Autozone still has the Wells unit. I don't want to wait until next week to get one from New York!

Vader, thanks for all your help man! I woulda been lost without it! I owe you a six-pack!

Vader

TA T&A,

Don't get too excited yet. If you had 12VDC at the MAF burn off terminal and had 4-5 V at the MAF output, the MAF may be O.K. Are you sure you didn't see the hot wire glowing?

Incidentally, Wells is headquartered in Fond du Lac - right at the bottom of LAke Winnebago (more cheesers). I'm not sure why you'd have to wait for New York... If you have a Blain's Farm & Fleet (not Mill's Fleet Farm) in your area you should be able to get one there for about $160.

T/A gets T&A

I'm absolutely certain there was nothing glowing inside that sensor at all. I called 10 out of the 13 fleet and farm's in the state, and they didn't have the MAF! They told me that they can't order it for me either. I don't know if that's just lazy employees or what. Well, I got a Bosch reman from Autozone. The car certainly does run much better and the code 36 has disappeared. There is still a bit of a stumble while accelerating...just a bit. I'm guessing that's because I've disconnected the battery countless times in the past week messing with the system. I may just need to readjust the TPS and IAC. I haven't checked the new sensor to see if the wire is glowing yet either. What else would you have thought it to be?

On a side note, the previous owner had installed a v-6 intake and left the hole for the air temp sensor OPEN! I plugged it with a copper plug when I got it. Maybe that was all the excuse the MAF needed to fail?

T/A gets T&A

This is getting just a little more than frustrating... The code 36 is back again today! What else do I have to do??? I've replaced the MAF, both MAF relays, the fuel pump relay, the oil switch, continuity checks on all the wires. The only thing left is the computer. Is that prone to failure on just one specific circuit such as this??? Vader, if you have any ideas I would certainly appreciate it.

edit: Hey...wait a minute. Is a code 36 related to ignition like I just read on the archive boards? Should I try to replace my new Accel ignition module with a stock one and see if that does anything?

T/A gets T&A

Well the stock ignition module is back in the car now. I took it for a test run and there was absolutely NO stumbling or hesitation from the throttle. It actually acted just like it was supposed to for once. And to think that I have put a new MAF and all new relays on there trying to fix the wrong thing. The old MAF may have been bad anyway adding to the problem, but for now, it seems that the Accel ignition module was the problem. I'll keep running the car a few times today and if it changes behavior or that damn code 36 comes back I will let you all know.

T/A gets T&A

Code 36 returned again...

The problem with the acceleration and stumbling seems to have been related to the ignition module. Once the old one went in, everything ran very well. I don't know if I did it when I changed the coil, but one of the clips is broken. The plug is still on the coil, but it's not really as tight as it could be. Might this cause a code 36 fault?

I ran the car home after the code 36 appeared again. I let the car run and took off the intake snorkel to look into the MAF sensor when I turned off the engine. It's dark out so I know I would be able to see if the hot wire glowed. I didn't see anything after the fuel pump cut off. I waited for about a minute and nothing. What is left for me to check with the burn off? In the diagram there are two or three places where the system grounds to the engine or chassis. Where exactly do they ground on the car? That's got to be the problem unless the ECM has a malfunction! Where can I find a good troubleshooting guide? Vader, any ideas?

Vader

T/A,

To recap (and in no particular order):

The MAF power relay is de-energizing, and the NC contacts are intact;

The MAF burn off relay is energizing, and you can meter 12VDC at both terminals 'D' and 'E' of the MAF;

The MAF generates at least a 3.0VDC signal at terminal 'C' when this occurs;

There is NO voltage at the auxilliary oil pressure (fuel pump voltage input at the ECM) switch while this cycle is in progress;

That should ba all that is necessary to achieve a "good" burn off cycle, from the perspective of the ECM. As long as the ECM connections are clean and intact, there should be no problems. Did you disconnect ECM power and clear the codes after the last repair?

The factory (Helm's) service manual has a troubleshooting flow chart for almost every error code diagnosis.

smiley23

I am glad you brought this post to the top t/a.

Vader, the information you are providing is rich!!! Thank you very much. The info you are providing is really helping out. I am getting the occational code 34 and the engine is stumbling at 70+mph and only in the hot weather (engine temp has no bearing on the problem).

https://www.thirdgen.org/techbb2/sho...hreadid=187418